M13 is the brightest globular cluster in the Northern Hemisphere and has approximately 300,000 stars where in these relatively crowded quarters the average separation is around one light year apart. It lies 23,000 ly from the Earth in Hercules. Backyard 6/20/2026 with a Planewave 17″ CDK telescope, ZWOAS2600 MC Pro Duo, Pixinsight and Photoshop. The big radio telescope at Arecibo Observatory sent a message to this cluster in 1974. Click on Message to M13
